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- Antibiotics:
- Sulfonamides
- Penicillins
- Cephalosporins
- Tetracyclines
- Aminoglycosides
- Macrolides
- Quinolones
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- Medications used to treat bacterial infections
- Culture and sensitivity before therapy
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- Empiric therapy: treatment of an
infection before culture
- Prophylactic therapy: treatment
with antibiotics to prevent an infection
- Broad spectrum- effective against several groups of microorganisms
- Narrow spectrum- effective against a few groups
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- Bactericidal: kill bacteria
- Bacteriostatic: inhibit growth of susceptible bacteria, rather than
killing them immediately; will eventually lead to bacterial death
- Superinfection: elimination of normal bacteria and other bacteria take
over
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- Hospital Acquired Infections
- Patients with decreased resistance
- Often drug resistant strains
- Staph (Skin, Lungs)
- Psuedomonas (Lungs, Wounds)
- Proteus (Wound, UTI)
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- One of the first groups of antibiotics
- sulfadiazine
- sulfamethizole
- Sulfamethoxazole
- sulfisoxazole
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- Bacteriostatic action
- Prevent synthesis of folic acid required for synthesis of purines and
nucleic acid
- Does not affect human cells or certain bacteria—they can use preformed
folic acid
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- Bactrim
- Combined with trimethoprim.
- Used to treat UTIs, Pneumocystis carinii pneumonia, ear infections,
bronchitis, gonorrhea, etc.
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- Photosensitivity
- Crystalluria
- Delayed skin reactions
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- Natural penicillins
- Penicillinase-resistant penicillins
- Aminopenicillins
- Extended-spectrum penicillins
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- Inhibit the synthesis of bacterial cell wall
- Bactericidal
- Therapeutic levels are not usually obtained in intraocular and
cerbrospinal fluid
- Rapidly excreted in through the kidneys
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- First introduced in the 1940s
- Bactericidal: inhibit cell wall
synthesis
- Kill a wide variety of bacteria
- Also called “beta-lactams”
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- Bacteria produce enzymes capable of destroying penicillins.
- These enzymes are known as
beta-lactamases.
- As a result, the medication is not effective.
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- Chemicals have been developed to inhibit these enzymes:
- These chemicals bind with beta-lactamase and prevent the enzyme from
breaking down the penicillin
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- Widely used
- Effectiveness and minimal toxicity
- Available IV & IM
- Natural PCN
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- Penicillin-beta-lactamase inhibitor combination drugs:
- amoxicillin + clavulanic acid = Augmentin
- Inactivate beta-lactamase enzymes
- Protects PCN and extends spectrum
- Available PO
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- Penicillins enter the bacteria via the cell wall.
- Inside the cell, they bind to penicillin-binding protein.
- Once bound, normal cell wall synthesis is disrupted.
- Result: bacteria cells die from
cell lysis.
- Penicillins do not kill other cells in the body.
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- Prevention and treatment of infections caused by susceptible bacteria
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- Allergic reactions occur in 0.7% – 8% of treatments
- urticaria, pruritus, angioedema
- 10% of allergic reactions are life-threatening
- and
- 10% of these are fatal
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- Common side effects:
- nausea, vomiting, diarrhea, abdominal pain
- Other side effects are less common
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- First Generation
- Second Generation
- Third Generation
- Fourth Generation
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- Semisynthetic derivatives from a fungus
- Structurally and pharmacologically related
to penicillins
- Bactericidal action
- Broad spectrum
- Divided into groups according to their antimicrobial activity
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- cefazolin cephalexin
- (Ancef and Kefzol) (Keflex and Keftab)
- IV and PO PO
- used for surgical prophylaxis, URIs, otitis media
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- Broad spectrum
- First generation
- Respiratory, soft tissue, bones, urinary tract, and bloodstream
infections
- Tx pcn resistant GC
- Contraindicated with prior severe anaphylactic reaction to PCN
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- doxycycline (Doryx, Doxy-Caps, Vibramycin)
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- Natural and semi-synthetic
- Bacteriostatic—inhibit bacterial growth
- Inhibit protein synthesis
- Stop many essential functions of the bacteria
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- Wide spectrum:
- gram-negative, gram-positive, protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme
disease
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- Bind to Ca2+ and Mg2+ and Al3+ ions to
form insoluble complexes
- Thus, dairy products, antacids, and iron
salts reduce absorption of tetracyclines
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- Strong affinity for calcium
- Discoloration of permanent teeth and tooth
enamel in fetuses and children
- May retard fetal skeletal development if taken
during pregnancy
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- Alteration in intestinal flora may result in:
- Superinfection (overgrowth of nonsusceptible organisms such as Candida)
- Diarrhea
- Pseudomembranous colitis
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- May also cause:
- Vaginal moniliasis
- Gastric upset
- Enterocolitis
- Maculopapular rash
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- Natural and semi-synthetic
- Poor oral absorption; no PO forms
- Very potent antibiotics with serious toxicities
- Bactericidal
- Kill mostly gram-negative; some
gram-positive also
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- Used to kill gram-negative bacteria such as Pseudomonas spp., E. coli,
Proteus spp., Klebsiella
spp., Serratia spp.
- Often used in combination with other antibiotics for synergistic effect.
- BIG GUN!!!!
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- Cause serious toxicities:
- Nephrotoxicity (renal failure)
- Ototoxicity (auditory impairment and vestibular [eighth cranial nerve])
- Must monitor drug levels, pg 581
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- Nephrotoxicity
- Ototoxicity
- Neurotoxicity
- Hypersensitivity
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- Ototoxicity and nephrotoxicity are
the most significant
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- Excellent oral absorption
- Absorption reduced by antacids
- First oral antibiotics effective against
gram-negative bacteria
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- Bactericidal
- Effective against gram-negative organisms and some gram-positive
organisms
- Alter DNA of bacteria, causing death
- Do not affect human DNA
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- Lower respiratory tract infections
- Bone and joint infections
- Infectious diarrhea
- Urinary tract infections
- Skin infections
- Sexually transmitted diseases
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- Dizziness
- Photosensitivity
- Constipation
- Rash, pruritis
- Flushing
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- Cimetidine
- Probenicid
- Antacids
- Iron
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- erythromycin
- azithromycin (Zithromax)
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- Strep infections
- Streptococcus pyogenes
(group A beta-hemolytic streptococci)
- Mild to moderate URI
- Haemophilus influenzae
- Spirochetal infections
- Syphilis and Lyme disease
- Gonorrhea, Chlamydia, Mycoplasma
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- GI effects, primarily with erythromycin:
- nausea, vomiting, diarrhea, hepatotoxicity,
flatulence, jaundice, anorexia
- Newer agents, azithromycin and clarithromycin: fewer side effects,
longer duration of action,
better efficacy, better tissue penetration
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- Before beginning therapy, assess drug allergies; other labs
- Be sure to obtain thorough patient health history,.
- Assess for conditions that may be contraindications to antibiotic use
- Assess for potential drug interactions.
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- It is ESSENTIAL to obtain cultures from appropriate sites BEFORE
beginning antibiotic therapy.
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- Patients should be instructed to take antibiotics exactly as prescribed
- Assess for signs and symptoms of superinfection:
- Fever
- Cough
- Perineal itching
- Sore throat
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- Check the name of the medication carefully since there are many agents
that sound alike or have similar spellings.
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- Each class of antibiotics has specific side effects and drug
interactions that must be carefully assessed and monitored.
- The most common side effects of antibiotics are nausea, vomiting, and
diarrhea.
- All oral antibiotics are absorbed better if taken with at least 6 to 8
ounces of water.
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- Sulfonamides
- Should be taken with at least 2400 mL of fluid
per day, unless contraindicated.
- Due to photosensitivity, avoid sunlight and
tanning beds.
- These agents reduce the effectiveness of
oral contraceptives.
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- Penicillins
- Monitor for 30 minutes.
- The effectiveness of oral penicillins is decreased when taken with
caffeine, citrus fruit, cola beverages, fruit juices, or tomato juice.
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- Cephalosporins
- Orally administered forms should be given with food to decrease GI
upset, even though this will delay absorption.
- Some of these agents may cause an Antabuse-like reaction when taken with
alcohol.
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- Tetracyclines
- Avoid
- 6 to 8 ounces of fluid, preferably water.
- Due to photosensitivity, avoid sunlight and
tanning beds.
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- Aminoglycosides
- Monitor peak and trough blood levels
- Symptoms of ototoxicity
- dizziness, tinnitus, and hearing loss.
- Symptoms of nephrotoxicity
- urinary casts, proteinuria, and increased BUN and serum creatinine
levels.
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- Quinolones
- Should be taken with at least 3 L of fluid per day, unless otherwise
specified
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- Macrolides
- These agents are highly protein-bound and will cause severe interactions
with other protein-bound drugs.
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- Monitor for therapeutic effects:
- Disappearance of
- Fever
- Lethargy
- Drainage
- Redness
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